Determination of glucose concentration by electroluminescence of an indium-tin oxide electrode

Glucose reacts with glucose oxidase to form gluconolactone and hydrogen peroxide (H₂O₂), and the glucose concentration may be determined indirectly from the amount of hydrogen peroxide produced. The authors have developed a method of H₂O₂ assay that uses the electroluminescence (EL) of indium-tin oxide (ITO). Since this method depends on a reversible reaction of the ITO itself, it does not require the addition of an emitting substance, allowing convenient continuous monitoring of the anylates. In the present work the triangular-wave potential was set at 0 - +1.4 - 0V against the Ag/AgCl reference electrode, and swept at a rate of 200 mVs^-1. The integrated number of photons was taken as the electroluminescence intensity, and its response to changes in H₂O₂ concentration was investigated. As a result a value that was dependent on H₂O₂ concentration was obtained. Electroluminescence intensity was measured varying the pH of the test solution from 7 to 13 with a Britton-Robinson buffer solution, and it was found that electroluminescence intensity was constant at pH9 and above. When glucose and glucose oxidase were mixed in the test solution, measurements of electroluminescence intensity showed a good correlation with glucose concentration.